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DEXMEDETOMIDINE. A SUMMARY
8
Sedation
One of the highest concentrations of α
2
A-receptors is found in the locus coeruleus (Figure
2). This core is located bilaterally in the upper part of the brain stem. Here lies a major centre
for the natural sleeping patron. Inhibition of noradrenergic activity in the locus coeruleus
creates an increase of the GABA and galanin in the brain. These inhibitory neurotransmitters
provide a central decrease of histamine secretion. Less occupation of histamine receptors in
subcortical areas leads to the state of hypnosis.
6
Figure 1.
α
2
-receptor (picture by courtesy of Ron Slagter)
Α
2
-receptors are located pre-, extra-, and postsynaptic. Presynaptic α2-receptors inhibits noradrenaline release,
postsynaptic α2-receptors influence effects on target tissue.
Figure 2.
Locus coeruleus (picture by courtesy of Ron Slagter)